1. Technical Field
The present invention relates to a rotating device and a robot arm device.
2. Related Art
In a rotating device including a rotating portion which rotates with respect to a fixed portion, a communication cable in which a signal is transmitted between a fixed side and a rotating side, a power cable to which power is supplied, a flexible pipe through which fluid such as air or liquid flows and the like pass in the vicinity of a rotation axis at which the fixed portion and the rotating portion are connected. In order to suppress a phenomenon in which these cables and flexible pipes expand and contract, or twist due to rotation operation, there is a case in which cables and flexible pipes are provided so as to pass through the inside of the fixed portion and the rotating portion. Or, for example, in the robot arm which deals with semiconductor products or food, there is a case in which cables and flexible pipes are provided so as to pass through the inside of the fixed portion and the rotating portion for avoiding generation of dust or dirt caused by cables or flexible pipes. Accordingly, many cables and flexile pipes are provided in the vicinity of the central axis of the rotation axis, which enlarges the size of the rotating device or sets a limit on a rotation angle.
For example, in JP-A-2002-280240 (Patent Document 1), a method is proposed, in which power is supplied by a transformer including coils at a fixed portion and a rotating portion respectively so as to sandwich a bearing, and transmitting communication of a signal is performed in a non-contact manner by a radio transmitter/receiver provided in the vicinity of the central axis of the bearing.
However, there is a case in which transmitting communication of a signal is performed in the non-contact manner as well as cables and flexible pipes to be connected between the fixed side and rotating side are provided so as to pass through the inside of the fixed portion and the rotating portion. In the method of Patent Document 1, since the radio transmitter/receiver as a communication means is provided in the vicinity of the central axis of the bearing, it is difficult to secure a spatial area passing through the inside of the rotation axis. Therefore, there is a problem that it is difficult to allow cables and flexible pipes to pass through the inside of the fixed portion and the rotating portion.